Sulfonic acid salts of acyloxyalkylamines

ABSTRACT

A sulfonic acid salt of an acyloxyalkylamine is prepared by reaction of an organic acid or amino-acid with a sulfonic acid salt of an alkanolamine. Isocyanates are prepared therefrom by reaction with phosgene.

This invention relates to the production of novel sulfonic acid salts ofacyloxyalkylamines (ester amine sulfonic acid salts) and thecorresponding isocyanates therefrom.

The ester amine sulfonic acid salts of the present invention arevaluable intermediates in the preparation of other compounds. They areof particular use in preparing isocyanates by phosgenation. The esteramine sulfonic acid salts, especially of polymerizable carboxylic acids,are of considerable interest in the preparation of polycationicpolymers, particularly as a source of poly-primary-amino functionality.The dibasic acyloxyalkylamine sulfonic acid salts may also be used ascuring agents for epoxy resins, either directly as the sulfonic acidsalt or as the hydrochloride salt to which the sulfonic acid salt isreadily convertible.

In copending U.S. patent applications Ser. Nos. 518,977 and 519,001,both filed Jan. 6, 1966, there is disclosed the preparation ofhydrochloride salts of ester amines by means of direct esterification ofsaturated carboxylic or aminoacids with alkanolamine hydrochlorides inthe presence of an excess of hydrogen chloride. Further disclosed is theconversion of the hydrogen chloride salts to isocyanates by reactionwith phosgene. The above applications, which are in the hands of acommon assignee and which are herein incorporated by reference, discloseprocesses which are a significant advance over the prior art; however,there are instances where the hydrochloride route is not suitable,either because the desired ester amine salt is produced in low yield orbecause a large amount of by products result.

The acyloxyalkylammonium sulfonate salt process of the present inventionis particularly useful in preparing unsaturated esters of alkanolaminesalts, such as the acrylic and methacrylic esters, from the unsaturatedacids. In the case of the hydrogen chloride route significant amounts ofby products, with unsaturated acids, are obtained because the hydrogenchloride tends to add across the unsaturation in the molecule. Thesulfonate salt process of the present invention is also useful with awide range of other organic acids and amino-acids, disclosed in moredetail hereinafter, and generally gives much faster esterification ratesat stoichiometric ratios of the alkanolamine salt and carboxylic acidreactants than any other known prior art procedure. Also, it has beenfound that there is improved mutual solubility of the alkanolaminesulfonic acid or sulfonate salt and the carboxylic acid reactants (ascompared with the hydrochloride salt route) especially in the presenceof an excess of sulfonic acid, and lower volatility of the sulfonicacid, thereby reducing losses and permitting the use of smaller excessesof acid. These advantages are particularly important from the standpointof avoiding the use of an excess of one or the other reactants, thusby-passing steps such as isolation and purification of the intermediateamine salts prior to phosgenation to the isocyanate. The low sulfonatenucleophilicity in the instant invention also minimizes thedecomposition or displacement of sensitive functional groups during thephosgenation reaction.

Now, in accordance with the instant invention, a process has been foundfor the direct esterification reaction of a free acid, an amino acid (orlactam) and an alkalolamine sulfonic acid salt to produce thecorresponding acyloxyalkylamine (ester) sulfonic acid salts. Inpreparing the ester amine sulfonic acid salt in accordance with theinstant invention, the alkanolamine is first converted to its acid salt.The resulting alkanolamine sulfonic acid salt is then reacted with thecarboxylic acid reactant preferably in the presence of an inert liquidor diluent. The carboxylic acid reactant and the alkanolamine sulfonateand sulfonic acid when present in excess must have a significantsolubility in each other under reaction conditions or else the inertliquid used as the reaction medium must be a mutual solvent for thesematerials. Where one of the reactants is a liquid or is molten under thereaction conditions, an excess of such reactant may be used as thereaction medium so long as such excess does not cause polymerization orpromote other undesirable side-reactions, i.e., such excess must act asan inert liquid.

At room temperature, the reaction between the materials is too slow tobe of practical significance. Generally, the reaction is carried outbetween about 40° C. and a temperature not higher than that at which thealkanolamine sulfonic acid salt dissociates into the free amine underthe conditions used (i.e. of pressure and other reactants present in themixture). Generally, the reaction temperature will be from about 50° C.to 200° C. and will be carried out in the presence of free excesssulfonic acid. Water is removed as the reaction progresses as bydistillation with a liquid such as benzene which forms an azeotrope withthe water. Generally, atmospheric pressure is preferred, but pressureseither higher or lower than atmospheric may be used. Preferably, thepressure is chosen so as to have the diluent at its boiling point at thetemperature used. Diluent need not necessarily be used; however, theesterification usually proceeds faster and goes further towardscompletion when the diluent is present. Suitable diluents or liquidreaction media include aromatic hydrocarbons, chlorinated hydrocarbons,chlorinated aliphatic hydrocarbons, chlorinated alicyclic hydrocarbon,etc. As specific examples, there may be mentioned toluene, benzene,xylene, ethylene dichloride, etc. Water also can serve as a convenientreaction media.

The comments above with respect to the carboxylic acid reactant alsoapply to the amino acid reactant and amino acid forming reactants (i.e.,lactams), except that the amino acid reactant is converted to itssulfonic acid salt prior to the esterification reaction with thealkanolamine salt reactant. In the esterification process, thealkanolamine component and the acid or amino acid component may be usedin stoichiometric equimolar amounts, or either component may be used inexcess.

In schematic form, and for illustrative purposes only, there is shownbelow in Scheme I, the general reaction outline involving an acid and analkanolamine salt, and the subsequent phosgenation to the correspondingisocyanate, in this case, 2-isocyanatoethyl methacrylate: ##STR1##

In the reaction scheme denoted as Scheme II, there is shown below, againfor illustrative purposes only, the general reaction involving an aminoacid, in its sulfonic acid salt form, with the alkanolamine salt, andsubsequent phosgenation to the corresponding isocyanate, in this case,2-isocyanatoethyl 6-isocyanatocaproate. ##STR2##

The alkanolamines which may be used in the instant invention containfrom 2 to 8 carbon atoms, have one primary or secondary hydroxyl groupand are primary amino group, and may include one oxygen or sulfur atomin the alkyl chain. The alkyl group of the alkanolamine may besubstituted with an inert substituent group as alkyl, phenyl, nitro,halogen, etc. Particularly preferred alkanolamines are ethanolamine,(2-amino-ethanol), 2-(2-aminoethoxy)-ethanol, 1-amino-2-propanol,2-amino-1-propanol, 2-methyl-2-amino-1-propanol, 3-amino-1-propanol, and2-amino-1-butanol. The ability of the present process to economicallyutilize a variety of alkanolamines permits the production of a varietyof acyloxyalkylamine sulfonic acid salts wherein the amine group may beattached to a carbon which can be primary, secondary or tertiary. Theisocyanates produced from these products will, in turn, offer a widerange of reactivities.

The sulfonic acids which are useful in the present invention include thecommonly available alkyl, cycloalkyl, alkaryl, and aralkylsulfonicacids, and the halogen substituted alkyl, cycloalkyl, alkaryl andaralkylsulfonic acids, particularly chlorine substituted. Representativeexamples of useful sulfonic acids, include alkanesulfonic acids such asmethanesulfonic acid, ethanesulfonic acid, etc., benzenesulfonic acid,napthalenesulfonic acid, p-chlorobenzenesulfonic acid,2,5-dichlorobenzenesulfonic acid, 3,4-dichlorobenzenesulfonic acid, andthe toluene sulfonic acids, ortho, meta and para. Alternatively, thesulfonic acids may be formed in situ in the reaction media by startingwith the corresponding sulfonyl chlorides, for example, benzenesulfonylchloride, and hydrolyzing them to the corresponding sulfonic acids.

The organic acids which may be reacted directly with the saidalkanolamines in the process of the invention are dicarboxylic ordibasic acids having at least two carbon atoms, e.g., oxalic acid,succinic acid and dibasic acids wherein the two carboxyl groups areseparated by a divalent aliphatic or alicyclic or aromatic group, thedivalent group having at least two and preferably three atoms betweenthe carboxyl groups, one of which atoms may be a hetero atom. Thefollowing acids are illustrative of those which may be used in thepresent invention: benzoic acid, the toluic acids; aliphaticα,ω-dicarboxylic acids having at least five carbon atoms as glutaric,adipic, sebacic, etc.; alicyclic dicarboxylic acid as1,4-cyclohexane-dicarboxylic acid; aromatic dicarboxylic acids aso-phthalic acid, isophthalic acid, terephthalic acid, diphenic acid,4,4'-diphenic acid, the phenylene diacetic acids, and2,7-naphthalenedicarboxylic acid and1,1,3-Trimethyl-5-carboxy-3-(p-carboxyphenyl)indane; dibasic acidscontaining a hetero atom as dinicotinic acid, diglycolic acid,thiodiacetic acid, p,p'-oxydibenzoic acid, the thiodialkanoic acidsproduced by reacting hydrogen sulfide with two moles of an unsaturatedacid such as acrylic, methacrylic, crotonic, cinnamic, etc.; and thethiodialkanoic acids produced by reacting sodium sulfide and an ester ofa halogenated acid. The oxygen and selenium analogs of thesethiodialkanoic acids can also be used. In addition to these generalclasses of acids which may be used, both oxalic and succinic acids havebeen found to be operable. Further, the acids may contain substituentswhich do not interfere with the reaction of this invention. Suchsubstituents include, for example, alkyl groups, aromatic groups,halogen groups as fluorine, chlorine, etc., nitro groups, etc. Examplesof such acids are α-butyl-glutaric acid, α-β-diethylsuccinic acid,p-chlorobenzoic acid, β-chloroglutaric acid, etc. In addition to theabove mentioned organic acids, the present invention is especiallyuseful with unsaturated acids, particularly, α,β-unsaturatedmonocarboxylic acids and unsaturated dicarboxylic acids. Preferredunsaturated acids are acrylic acid, methacrylic acid, fumaric acid,maleic acid and other unsaturated acids mentioned in U.S. Pat. No.2,718,516. The anhydrides of the various acids given above may also beused as the organic acid component in the present invention. Preferredanhydrides are phthalic anhydride and maleic anhydride.

The amino acids which are useful in the invention are themonoamino-monocarboxylic acids, the monoamino-dicarboxylic acids, thediamino-monocarboxylic acids, diamino-dicarboxylic acids and lactamshaving 3 to 12 carbon atoms in the ring.

The amino acids which may be used in the instant invention may be eitheroptically active or inactive and include monoamino-monocarboxylic acidssuch as alanine, isoleucine, 3-aminobutyric acid, 3-aminopropionic acid,3-amino-2-methyl propionic acid, phenyl alanine, p-aminobenzoic acid,methionine, ω-amino acids generally, etc.; monoamino-dicarboxylic acidssuch as aspartic acid and glutamic acid; diamino-monocarboxylic acidssuch as lysine and ornithine; diamino-dicarboxylic acids such aslanthionine; and lactams such as ε-caprolactam, β-methyl-β-butyrolactam,α,β-dimethylbutyrolactam, α,α',β-trimethylbutyrolactam,β-carbomethoxy-butyrolactam, β-phenyl-β-propiolactam,β-methyl-β-caprolactam, β-methyl-β-valerolactam, β-ethyl-β-valerolactam,2-pyrrolidone, 6-methyl-2-piperidone, 3-methylcaprolactam and7-methyl-caprolactam. The amino acids may be substituted with inertsubstituent groups as alkyl, nitro, halogens, etc. and may contain oneor more hetero atoms which do not interfere with the esterificationreaction, and, where applicable, the subsequent phosgenation. Mixturesof amino acids may be used. The diaminomonocarboxylic acids disclosed inFrench Pat. No. 1,351,368 may be used. Amino acids occur widely innature and a number of synthesis methods are available for theirproduction from inexpensive raw materials. Thus the addition of ammoniato an unsaturated acid may be used to produce inexpensive amino acidsfor use in the instant invention. When a lactam is used as the aminoacid, desirably water (preferably at least one mole per mole of lactam)is added along with the sulfonic acid component to facilitate openingthe ring. An undue excess of water is to be avoided since it must beremoved during the esterification. The lactam may be first added incontact with the water-acid mixture and then the alkanolamine addedalong with an inert organic liquid and an azeotropic agent and the esterprepared as above. Alternatively, all the reactants may be chargedinitially, the mixture heated without removal of water for a sufficienttime to open the ring, and then the water is removed causingesterification to proceed. Other variations may also be used, ascharging the lactam after the alkanolamine is charged, or initiallycharging all the materials except the azeotropic agent which is addedafter ring opening.

Where the acyloxyalkylamine sulfonic acid salt is to be converted to thecorresponding isocyanate, the conversion is carried out with phosgene orother carbonyl dihalide. The phosgene may be employed in either liquidor gaseous form. In the phosgenation reaction, the acyloxyalkylammoniumsulfonate or sulfonic acid salt is dispersed in an inert, liquidreaction medium, phosgene added, preferably in excess of that needed toreact quantitatively with the amino groups, and the temperature of thereaction medium maintained from about 60° C. to about 225° C. The molarratio of phosgene: acyloxyalkylammonium sulfonate may be from 1.1:1 to10:1 and preferably is at least 2:1. Suitable liquid reaction mediainclude aromatic hydrocarbons, chlorinated aromatic hydrocarbons,chlorinated aliphatic hydrocarbons, chlorinated alicyclic hydrocarbons,etc. The phosgenation may also be carried out in steps. The esterreaction product of the acid--or amino acid-alkanolamine sulfonatereaction may be used as such for the phosgenation i.e., without anyseparation as heretofore noted, or, if desired, the acyloxyalkylammoniumsulfonate may first be purified and the purified product phosgenated.

Representative uses of the acyloxyalkylamine sulfonic acid salts of theinvention are disclosed supra. The isocyanates produced therefrom may beused as cross-linking agents for polymers containing active containingactive hydrogen groups, may be reacted with low molecular weightpolymers containing active hydrogen groups such as hydroxyl-terminatedpolyesters or polyethers to produce polyurethanes, and may be added topolymeric compositions to improve the adhesion thereof to a variety ofsubstrates, particularly metallic substrates. They are also useful asintermediates in producing other novel compounds useful as modifyingagents for textiles, cellulose, starch, polyvinyl alcohol, algin,copolymers of hydroxyalkyl esters of unsaturated acids, etc.

The following examples are by way of illustration and not of limitation.All parts and percentages are by weight unless otherwise specified. Alltemperatures are in degrees Centigrade.

EXAMPLE 1 Preparation of 2-aminoethyl 6-aminocaproate,bis-benzenesulfonic acid salt

A 4-necked, Morton-type (indented) flask is fitted with a mechanicalstirrer, a thermometer, a reflux condenser, and a pressure equalizingdropping funnel. The flask is charged with 180 g (10.0 moles) of waterwhich is then heated to 90° C. Keeping the temperature between 90° and110°, 530 g (3.00 mole) of benzenesulfonyl chloride are added graduallyover a one-hour period to hydrolyze it to benzenesulfonic acid andhydrogen chloride. Toward the latter part of the addition, vigorousevolution of hydrogen chloride is observed. After stirring at 100° for0.5 hr., the mixture is cooled to 50°, and 113.2 g (1.00 mole) ofε-caprolactam and 61.1 g (1.00) of 2-aminoethanol are charged. Themixture is then held at 115° for 6 hours to hydrolyze the caprolactam toaminocaproic acid. Most of the water is then stripped off under reducedpressure (16 mm.) with heating on the steam bath. Then the refluxcondenser is replaced by a Dean-Stark water separator trap andcondenser, 180 g of xylene are added, and the mixture is heated underreduced pressure so as to reflux at 110° (ca. 328 mm. Hg. pressure).After azeotroping off water for 8-10 hours, the esterification isessentially complete. The product can be isolated by crystallizationfrom isopropanol, m.p. 142°-143°. Anal. Calc'd for C₂₀ H₃₀ N₂ O₈ S₂ : C,48.96; H, 6.16; N, 5.71; S, 13.07. Found: C, 48.67; H, 6.10; N, 5.25; S,11.99.

EXAMPLE 2 Preparation of 2-Isocyanatoethyl 6-isocyanatocaproate

It is not necessary to isolate and purify the sulfonic acid salt of theaminoester from the crude reaction mixture prior to phosgenation andconversion to the isocyanate. Instead, the crude esterification reactionmixture, along with an excess sulfonic acid, may be reacted withphosgene directly to produce the isocyanate.

Thus, the product of Example 1, as a suspension in the xylene diluentemployed for the esterification, is cooled to 100°, and phosgene ispassed in at the rate of 1 mole per hour. After approximately 3-4 hours,the suspended melt is transformed into a crystalline solid. After anadditional 1-2 hours of phosgenation at 100°, 1.5 ml. ofdimethylformamide is added and the temperature is raised to 115°.Phosgenation is continued for about 8 hours more until the mixture ispractically free of suspended solid. The yield of the isocyanate,2-isocyanatoethyl 6-isocyanatocaproate, is (according to vapor phasechromatographic analysis) typically 70-90% largely depending upon howcomplete the esterification reaction had been. The benzenesulfonylchloride is produced in nearly quantitative yield.

EXAMPLE 3 Preparation of 2-Aminoethyl Methacrylate,3,4-Dichlorobenzenesulfonic Acid Salt

A 1-liter flask containing 1.10 moles of 3,4-dichlorobenzenesulfonicacid, 1.00 mole of methacrylic acid, 1.00 mole of ethanolamine, 270 g ofxylene, and 1 g of diphenylphenylenediamine polymerization inhibitor, isfitted with a mechanical stirrer, a thermometer, a Dean-Stark waterseparator trap and condenser, and is set up for reduced pressureazeotropic distillation.

Water is azeotroped off at 80° (ca. 110 mm. Hg. pressure) for 17-20hours until the esterification is essentially complete. This reactionmixture is suitable for reaction with phosgene to prepareisocyanatoethyl methacrylate.

If desired, the pure 2-aminoethyl methacrylate,3,4-dichlorobenzenesulfonic acid salt may be isolated and purified byrecrystallization from a xylene-isopropanol mixture, m.p. 147°. Anal.Cal'd for C₁₂ H₁₅ NO₅ Cl₂ S: C, 40.45; H, 4.21. Found: C, 40.98; H,4.36.

EXAMPLE 4 Preparation of 2-Isocyanatoethyl Methacrylate

To the reaction mixture of Example 3 is added 25 g of 1,2-dichloroethaneand 3.5 g of dimethylformamide. Keeping the temperature at 70°, phosgeneis passed in at the rate of 0.5 mole/hr. for 6-8 hours, addingadditional dimethylformamide as follows: 0.05 mole at 1.0 hour, 0.01mole at 2.0 hr., and 0.03 mole at 3.0 hr. At the end of this period, themixture is sparged with dry air at 120° for 4 hours. The product isisolated by careful functional distillation through a short Vigreauxcolumn. The cut boiling 65°-85° (1-2 mm.) corresponds to pure (99%)2-isocyanatoethyl methacrylate. A later cut, b.p. 85°-130° (1-2 mm.) is3,4-dichlorobenzenesulfonyl chloride.

EXAMPLE 5 Preparation of 2-Isocyanatoethyl Methacrylate

This example illustrates the phosgenation of pure 2-aminoethylmethacrylate, p-chlorobenzenesulfonic acid salt.

A 1-liter, 5-necked flask is fitted with a mechanical stirrer, a gasinlet tube, and a thermometer. The flask was charged with 162 g (0.50mole) of pure 2-aminoethyl methacrylate, p-chlorobenzenesulfonic acidsalt, 250 g of heptane, 50 g of 1,2-dichloroethane, 3.5 g ofdimethylformamide, and 1 g of diphenylphenylenediamine.

Air (20 ml/min) and phosgene (0.5 mole/hr.) are passed into the stirredmixture at 70° until the phosgenation is complete (ca. 6 hrs.) Vaporphase chromatographic analysis at this time indicates the yield of2-isocyanatoethyl methacrylate to be essentially quantitative.

Table I Additional Examples of Sulfonic Acid Salts of Aminoalkyl Esters

In Table I are given the melting points, and elemental analyses ofrepresentative aminoalkyl ester sulfonic acid salts prepared by directesterification of carboxylic acids (or anhydrides wherein indicated)with the sulfonic acid salt of the alkanolamine. All of the reactionsare carried out using an inert diluent to aid in the removal of water,while operating at the reflux temperature of the diluent, and atatmospheric or lower pressure. (Previous examples have demonstrated thatit is not necessary to operate at atmospheric pressure, and that anypressure giving a convenient boiling point for a particular diluent maybe used.) In the examples in Table I, an excess of sulfonic acid isemployed (10% in most examples), and the carboxylic acid (or anhydride)is added directly to the mixture, except for the first entry(2-aminoethyl 6-aminocaproate bismethanesulfonic acid salt) where theamino acid is generated in situ by hydrolysis of caprolactam. Sulfonicacid is either added as the free acid or made in situ by hydrolysis ofthe sulfonyl chloride as, for example, was illustrated in Example 1. Thereactions in Table I are run at temperatures ranging from 80° C. to 180°using as diluents benzene, toluene, xylene, and mixtures of xylene andsulfolane. In the case of the unsaturated esters, the sulfonic acid,where generated in situ, from the hydrolysis of sulfonyl chloride, isfirst dried azeotropically with the diluent to insure the removal ofhydrogen chloride. (The reference to an excess of a sulfonic acid, inthe specification and in the claims, refers to that quantity of asulfonic acid which should be present during the esterification reactionand which is in excess of that required to form a sulfonic acid saltwith the alkanolamine and with the amino acid (or lactam) when present.Ordinarily, this excess will vary between about 5 to 200 mole percentand, more preferably, from about 10 to 100 mole percent).

                                      TABLE I                                     __________________________________________________________________________    Additional Examples of Sulfonic Acid Salts of Aminoalkyl Esters               Carboxylate Species            * Elemental Analysis                           Used as Starting          Melting                                                                            (Calculated over Found)                                                                   Esterification                     Ex.                                                                              Material  Product      Point                                                                              C   H   N   Temp. (Pressure)                                                                       Diluent                   __________________________________________________________________________     6 caprolactam                                                                             bis-methanesulfonic                                                                        115°-116°                                                            32.77                                                                             7.15                                                                              7.65                                                                              118°                                                                            35/65 (w/w)                            acid salt of 2-amino-                                                                           32.48                                                                             7.08                                                                              7.00                                                                              (atmospheric)                                                                          toluene/                               ethyl 6-aminocaproate                  xylene                     7 acrylic acid                                                                            benzenesulfonic acid                                                                       115°                                                                        42.93                                                                             4.55                                                                              4.55                                                                              80°                                                                             benzene                                salt of 2-aminoethyl                                                                            43.02                                                                             4.58                                                                              4.50                                                                              (atmospheric)                                   acrylate                                                          8 methacrylic acid                                                                        benzenesulfonic acid                                                                       135°                                                                        50.17                                                                             5.92    80°                                                                             benzene                                salt of 2-aminoethyl                                                                            50.50                                                                             5.87    (atmospheric)                                   methacrylate                                                      9 methacrylic acid                                                                        2-naphthalenesulfonic                                                                      155°                                                                        56.97                                                                             5.64    111°                                                                            toluene                                acid salt of 2-amino-                                                                           56.64                                                                             5.58    (atmospheric)                                   ethyl methacrylate                                               10 methacrylic acid                                                                        p-chlorobenzenesulfon-                                                                     162°                                                                        44.79                                                                             4.98    80°                                                                             xylene                                 ic acid salt of 2-                                                                              44.66                                                                             5.07    (110 mm.)                                       aminoethyl methacrylate                                          11 methacrylic acid                                                                        2,5-dichlorobenzene-                                                                       153°                                                                        40.45                                                                             4.21    80°                                                                             xylene                                 sulfonic acid salt of                                                                           40.81                                                                             4.32    (110 mm.)                                       2-aminoethyl methacry-                                                        late                                                             12 p-aminobenzoic                                                                          bis-benzenesulfonic                                                                        233°                                                                        50.81                                                                             4.84                                                                              5.65                                                                              140°-160°                                                                50/50 (w/w)                  acid      acid salt of 2-amino-                                                                           51.76                                                                             4.95                                                                              6.01                                                                              (atmospheric)                                                                          xylene/                                ethyl p-aminobenzoate                  sulfolane                 13 terephthalic acid                                                                       bis-benzenesulfonic                                                                        258°                                                                        50.70                                                                             4.93                                                                              4.93                                                                              145°-180°                                                                50/50 (w/w)                            acid salt of bis-2-                                                                             50.81                                                                             5.03                                                                              5.02                                                                              (atmospheric)                                                                          xylene/                                aminoethyl terephthalate               sulfolane                 14 phthalic anhydride                                                                      bis-benzenesulfonic                                                                        187°                                                                        50.70                                                                             4.93                                                                              4.93                                                                              140°                                                                            xylene                                 acid salt of bis-2-                                                                             50.80                                                                             4.86                                                                              4.99                                                                              (atmospheric)                                   aminoethyl phthalate                                             15 maleic anhydride                                                                        bis-benzenesulfonic                                                                        191°                                                                        46.33                                                                             5.01                                                                              5.40                                                                              140°-165°                                                                xylene                                 acid salt of bis-2-                                                                             46.91                                                                             5.21                                                                              5.17                                                                              (atmospheric)                                   aminoethyl fumarate                                              __________________________________________________________________________     *C = Carbon                                                                   H = Hydrogen                                                                  N = Nitrogen                                                             

What is claimed is:
 1. An alkyl, cycloalkyl, alkaryl, aralkyl, orhalogen-substituted alkyl, cycloalkyl, alkaryl, or aralkyl sulfonic acidsalt of 2-aminoethyl methacrylate or 2-aminoethyl acrylate. 2.Composition of matter according to claim 1 wherein the salt is the3,4-dichlorobenzenesulfonic acid salt of 2-aminoethyl methacrylate. 3.Composition of matter according to claim 1 wherein the salt is thebenzenesulfonic salt of 2-aminoethyl methacrylate or 2-aminoethylacrylate.
 4. Composition of matter according to claim 1 wherein the saltis the 2-napthalenesulfonic acid salt of 2-aminoethyl methacrylate. 5.Composition of matter according to claim 1 wherein the salt is thep-chlorobenzenesulfonic acid salt of 2-aminoethyl methacrylate. 6.Composition of matter according to claim 1 wherein the salt is the2,5-dichlorobenzenesulfonic acid salt of 2-aminoethyl methacrylate. 7.An alkyl, cycloalkyl, alkaryl, aralkyl, or halogen-substituted alkyl,cycloalkyl, alkaryl, or aralkyl sulfonic acid salt of a primary aminoalkyl ester of an aliphatic dicarboxylic acid, an aromatic dicarboxylicacid, acrylic acid, or methacrylic acid.
 8. A sulfonic acid saltaccording to claim 7 wherein the amino alkyl ester is 2-aminoethylmethacrylate, or 2-aminoethyl acrylate.